Our school requires an exit exam aka placement test every year for Math classes starting 3rd grade and continuing through HS. It is possible for a kid to take Algebra or another HS level class, get good grades, and fail the exit exam. They do get a second chance at the test in early August if they fail in the spring. They recommend retaking a class or non honors track to students that fail the 2nd test. It doesn't happen often, but it does occasionally. It keeps the teachers in check from grade inflation.
I would inquire if all students are being assessed or just yours. In our district all of them are being assessed every year.
It seems a bit unfair to punish the kids for the teacher's dishonesty. If you pass the course it seems reasonable you should be able to go to the next level. If you pass the course but not the test then either the teacher has been inflating the grade or the has been teaching and assessing the wrong stuff - not the students fault.
